Ohio is about to send its first military units into the war the United States has declared on terrorism.

The Air Force's congressional liaison office has notified Ohio's 21 congressional offices that two units could be activated quickly.

They are:

The 424 members of the Ohio Air National Guard's 121st Air Refueling Wing, based at Rickenbacker Air National Guard Base near Columbus.

The 211 members of the Air Force Materiel Command, a reserve unit at Wright-Patterson Air Force Base in Dayton.

Friday afternoon, officials of the Ohio Air National Guard and the Air Force Reserve said no activation orders had been issued.

The military routinely notifies members of Congress when Guard or reserve units from their state are about to be called up.

According to the e-mail, the reservists based at Wright-Patterson could be assigned to Operation Noble Eagle, the military's homeland defense program in the wake of last week's terrorist attacks.

The 121st Air Refueling Wing, congressmen were told, could be activated for duty in Operation Infinite Justice, the military deployment that began Wednesday to retaliate against the terrorists responsible for the airline hijackings.

Only a small fraction of the Ohio Air National Guard units are to be called to active duty, according to the Air Force e-mail.

The refueling unit has about 1,400 members who live all over the state. Its KC-135 tanker planes refuel jet fighters and bombers in the air.

It has been one of the most active Guard units in Ohio in recent years, with its members dispatched to nearly every hot spot that has sprung up around the world over the past decade.

The Air National Guard unit was activated in the Persian Gulf War in 1991, as was the Air Force Materiel Command at Wright-Patterson.

The 121st Air Refueling Wing did voluntary stints in Somalia in 1993 and the U.S. enforcement of the no-fly zone in Iraq the following year.

The Guard unit performed the same task in 1995 and 1996 in the U.S. enforcement actions in Bosnia. The 121st was back in the Middle East in 1998 and 2000, supporting U.S. fighter squadrons in another U.S. mission to enforce the Iraqi no-fly zone.

If activated, the two air units will be the first from Ohio in an effort that has seen more than 5,000 reservists and Guardsmen activated so far.

The Department of Defense has plans to call up 35,500 reservists and Guardsmen, which means that Ohio units are almost certain to be activated.

Ohio has about 15,000 Guard members and about 15,000 military reservists.

There are more than 20 Guard units in Kentucky and several military reserve units, mostly in Frankfort and Fort Knox, but none has been in the initial call-ups of reserve and Guard troops.